Telephone-exchange system.



F. E.' ANDERSON.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED mms. 191B.

1,279,489, Patented sept. 24,1918.

Frede/vdr f. #Hdez/.5 0/1 FREDERICK E. ANDERSON-lor NEWARK, JERsYQ AssIciiiioR tro lwins'.lniRNgjeLnev TRIO COMPANY, INCORPORATED, OP NEW YORK, N. Y., A CORPORATION or YORK.

Speccatonof Letters Patent.y 24, 1918.5

Application filed January s, 191s. 'serial No. 215,863.'

To all whom it may concern.' l

Be it known that I,- FREDERICK E. AN- DnRsoN, a citizen of the United States, residing at Newark, in the-county of Essex, State of New Jersey,lhave invented certain new and-useful Improvements-in Telephone- EfXchange Systems, of whichthe following is a full, clear', concise, `and eXact description.v A,

This invention relates to telephone eX- change systems and ,more particularly to such systems employingv trunk circuitsextending from` operatorsy positions of a switchboard to chief operators desks, in-

formation and supervisory operators positions and like positions. Y

The` object of this invention is to yprovide improved signaling means for such systems. In accordance withone feature ofthisvinvention, a trunk circuitequippedwith a key at the desk. end for opening-and closing a direct'current bridgeof the talking circuit to causethe operation of-a signaling device in .the connected link circuit at thel switchboard, is provided with a: condenser, a relay and circuit'connections 'which coperate upon the actuation of the key to reduce to a minimum the usual disagreeable clicks to the desk operator whose telephone set is at the time connected with theV .trunk circuit and to the subscriber whose line,qat that time, may be connected with the other end of the link circuit. Y

In accordance with another feature of this invention, the desk end of the trunk circuit is provided with a relay which in operating under control of a key, is bridged across and holds the trunk circuit while the desk oper.- ators telephone set is disconnected therefrom to enable the operator to attend to other duties, and is disconnected from' the trunk circuit when the desk operators telephone set is again connected therewith.-

For a more complete understanding of this invention, reference should be had to the following descriptionconsidered in connection with the accompanying drawing illustrating one embodiment thereof.

There is shown in the drawing, a telephone line A. eXtending to a central office where it be. 'connected in any suitable manner with a cord circuit B, Vwhich may be employed to connect the telephone line A with swering4 operators position of the switch-I, board at which telephone line A, terminates,

` a trunk lcircuit @extending-from. the,v an-v `i' to an informationoperators desk. yThe app paratus shown tfo the left-ofi'thedotted line 2-2is associated with the answering operatorsv position, and that shown to the, right of this dotted line is associatedV with the information operators desk. Itis thought that the nature of this invention-is such that it can Abe well understood from va description` of the operationl ofthe system shown in the drawing, and it will be so described-.

Subscriber A having initiated a call and the answering end of the cord circuitB having been connected therewith inany wellknown and lsuitable manner, Vthe operator actuates listening key 6 to conne'ctthe oper# ators telephone ,set with the 'calling line. Upon beingl advised that fthecalling subscriber desires to converse vwith theinforma- .tion operator, the switchboard operator-recoi stores thelistening key 6 to normal position and inserts. calling plug 7 into'jackS of the trunk circuitC.y nCalling Lsupervisory lamp 9 Yis thereupon lighted and relay 10 is-oper; ated. Relay 10,in operating, causes the lenergization of ringing relay 11 over a circuit from battery throughresistance 12, vthe winding of ringing relay 11.normal c011- tacts of relay ldand triprrelay 13, and the Contact of relay 410 to ground'.V Ringing relay 11, upon bei-ng energized, connects a source ofl rlnging A'current 14 throughv the winding of trip relayv 13 tolthe trunk circuit for causing the operation of-acall 4bell 15 l located at the information operators desk i Q K* .f

The information operator in responseto the operation of the call bell 15, inserts plugs 20 and 21 into therijacks 22 and 23. To the sleeve contacts of the plugs20 and 21 lis con'- nected the receiver 24, and to the tip ,contacts thereof is Connected the transmitter 25 of the information operators telephone set. These plugsmay forml a twin plugby being securelyheldv together inl the manner jdisclosed, eitherlin the Patent No.1,039,1567 to Lyng or in Patent No. 1,101,731 to De Vignier.I When those two plugs form a twin plug,'the acks 22 and 23 should be mounted close together tobe simultaneously engaged by the plugs. The insertiony of the plug 2,0

into the .j ack 22 causes the closure of a local contact 26, and the insertion of plug 22 into jack 23 causes the closure of a local contact 27. The closure of local contact 27 after the engagement of the tip contacts of the plugs and jacks insures that the receiver circuit is established after the transmitter circuit is closed, thereby eliminating clicks tothe op- Y f 32 connected in parallel with a portion thereof. This path is of sufliciently low impedance to permit the operation of trip relay 13. This trip relay 13 in operating opens the short-circuit about the winding of relay 16 which immediately operates, establishing a locking circuit for itself and a short-circuit about the winding of'ringing relay 11, which thereupon releases, disconnecting the source of ringing current 14 from the trunk circuit. Upon the release of the ringing relay 11, supervisory relay`33 is operated to establish a shunt circuit including resistance 12 about the `calling supervisory lamp 9, thereby extinguishing the lamp. Relay 32 may close its contact when traversed by ringing current from the source 14 but ifit does not then close its contact, it becomes fully energized when-the source of direct current is substituted for the source of ringing current. VRelay 32 upon being fully energized,

closes energizing circuits through a Vfast operating and slow releasing relay 34 and through a slow operating relay 35.l The circuit for relay 34 may be traced from battery through the windingof relay 34, normal contact of relay 35, lower normal contact of relay 36 and the contact of relay 32 to ground. The energizingcircuit of relay 35 may be. traced from battery through the winding of relay 35,v upper normal. contact of relay 36 and the contact of relay 32 4to ground.

Fast operating relay 34 in attracting its armatures opens its contacts, the right-hand `Contact being in the energizing circuit of relay 36. Slow operating relay 35. upon attracting its armature opens the circuit of re layV 34 and closes a contact in the energizing circuit of relay 36, so that upon the release of slow releasing relay 34, relay 36 is operated over a circuit from battery through the winding of relay 36, righthanldcontact of relay 34,.alternate contact of relay 35, lower contact of relay 36 and contact of relay 32 to ground. Relay 36 in operating closes its middle alternate contact, thereby establishing a locking circuit for 'itself through the contact of relay 32 to ground. The opening of the normal contacts of relay 3.6, opens the energizing circuits of both relays 34 and so that these relays cannot be energized again until after the release of relay 36. Re-

lower alternate contacts, thereby connecting the operatorstelephone set with the trunk circuit. In this way by delaying the closure of the upper and lower alternate contacts of relay 36, until after ringing current has been disconnected from the trunk circuit and di.- rect current has been substituted therefor', the usual severe clicks in the operatorsreceiver, -due to the disconnection of the ringing current, are avoided. y

-Afterrhaving conversed'with the calling subscril'ern, the information oper'atormay desire to signal the operator at the switch# board in order to give the switchboard operator instructions for K completing another connection for subscriber A. This signaling of the operator at the switchboard is accomplished by the repeated -actuation of the flashing key 30 to* cause the intermittent lighting of the calling supervisory lamp 9. This key is constructed so thatrwhen operated, its middle contact 4G is first closed, its lower contact 41 is then' opened, andiinally its upper contact 42 is opened. When the key is restored to normal position, contact 42 is first closed, then contact 41k is closed, and finally contact 40 is opened.A Upon the actuation of this flashing key 30,-the closure of its contact140 causes the energization of a fast operating and slightly slow releasing f relay 43, which opens its lower and closes its upper contact. The opening of the lower contact introduces a break in circuit' of the operators receiver 24, and the closure of the upper contact establishes a holding circuit for relay 36 in parallel with its middle alternate contact and the contact of relay 32. The opening of contact 41 ofthe key 30 introduces another break in circuit with the operators receiver 24, and the opening of contact 42 opens the direct current bridge across the trunk circuit which includes the retardation coil 31 and the relay 32:, relay 32 thereupon releases its armature.

The inductive discharge from the portion of the retardation coil 31 included in parallel with the winding of the relay 32, serves to render the relay quick in releasing; Upon the opening of contact 42, a condenser 44v is included in circuit with the retardationcoil 31 and the relayk 32. The inductive disV- charge from the impedance coil connected across thetrunk circuit surges over the trunk circuit and would ordinarily cause, through the inductive action of the repeating coil in Vlay 36 in operating, also closes its upper and ico Y iis the cord circuit, a very severe click in the re- J 42, this condenser, which is not at that time charged, becomes charged, due to` the inductive discharge of thev retardation coil, and thereby serves effectively to reduce the click to the calling subscriber.

' Since the operators receiver 24 is disconnected from the trunk circuit before contact 42 is opened, this inductive discharge from the retardation coil 31 does not find a path through the operators receiver 24. The opening of the direct current bridge across the trunk circuit upon the opening `of contact 42, causes the release of supervisory relay 33, whereupon the calling supervisory lamp 39 is lighted.

kThe restoration of key 30 to normal position causes the closure of contact 42, which restablishes the direct current bridge across i the trunk circuit and provides a discharge path for the condenser 44. Immediately upon the establishment of this bridge, supervisory relay 33 is energized to efface thel lamp 9, and relay 32 is operated to close its contact. The'closure of contact 42 is then followed by the closure of contact 41, and finally contact 40 is opened, thereby releasing relay 43, which opens its upper and closes its lower contact. Relay 32 is energized upon the reestablishment of the direct current bridge across the trunk circuit, and'closes its contact before relay 43 releases, so that relay 36 is held operated. Since the lower Contact of relay 43, which is in circuit with the operators receiver 24 closes after the establishnient of the direct current bridge, there isA no surge of current through' the operators receiver when this lower contact of relay 43 is closed. In this way the clicks to the information operator are lreduced to a minimum.

While the plugs 20 and 21 engage the jacks 22 and 23 and the flashing key '30 is in normal position, the switchboard operator may, by withdrawing the plug 7 from the jack 8 and immediately'reinserting it therein, attempt t0 re-ring the information operator.

lVhen the plug 7 is withdrawn from the jack phone set remains disconnected from they trunk circuit until after ringing current has been disconnected therefrom and the source of direct current substituted therefor. Therefore the usual ysevere clicks Vvattending"the tripping of theringing current from-an automaticringing cord circuit are prevented.'v

The inductive discharge ofthe portion of the retardationvcoil'31 which is Vconnected in parallel with the winding of relay 32 through that winding, serves to speed upthe'V release of this relay when the plug 7 is withdrawn from the' jack V8, thereby insur-l ing that the information operators telephone set'will be disconnected from the trunk cir-n cuit when ringingv current is connected to the trunk circuit upon the reinsertio'n of the v plu r 7 into the jack 8.

i? While ai@ pings A2o and ei are' inserted inthe jacks 22 and 23, and the cord circuit is connected with the trunk circuit, the information operator finds that she must disconnecttherefrom and attend to other duties for the moment, the connection over [the trunk circuit may be held and the supervisory lamp 9 may be maintained eaced while the information operators telephone set is disconnected from the trunk circuit."` @This may be accomplished by the momentary actuation of the key 50,:wliich in beingoperated uconnects a'relay 51 across the-talking strands of the'trunk circuit. This relay 51 is thereupon energized and'closes its contact, y' y thereby establishinga locking :circuit for a5 itself,fwhicli includes the left-hand contact of the fast operating and slow releasing -relay 34. After this key 50 has been momen'- tarily actuated and the relay 51 locked up, the information operators plugs may be ido withdrawn from the jacks. Relay 32 thereupon releases, followed by the releaseo'f relay 36 which opens its upper :and lower alternatecontacts, which aref in circuit with the operators telephone set. Later when 5 the informationop'erator reinserts the plugs within the jacks, the closure of contact v26 causes the' operation of relay 32, whereupon relays 34, 35 and 36`operate'- in the -inanner hereinbefore described to connect the operators telephone set with the trunk circuit. The operationof relay 34 opens the locking circuit lof relay 51 which is thereupon disconnected` from the trunk circuit' and releases its armature. l

` Vhatis claimed is:

-1. vA telephone exchangefsystem comprising a trunk circuit includingy a' pair of talking vconductors extending from a first to a secondi switchboard, a telephone set, a link r19.0 circuit connecting 'the telephone set with the trunk circuit, a signaling device for the i link circuit, a direct current inductive bridge for the talking conductors, a manually operated switch at the second switchboard controlling the operation of the signaling device and adapted when actuated to interrupt the inductive bridge, and a condenser included in circuit with the inductive bridge upon the actuation of the switch to absorb the charge l Vsecond switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device for the link circuit,`

an operators telephone set at the second switchboard having the receiver thereof con-Y nected withthe talking conductors, a direct current inductive bridge for the talking conductors, a manually operated switch at the second switchboard adapted when actuated to open the bridge thereby to cause the operation of the signaling device, andv means responsive yto the actuation of the switch to open one of the talking conductors extending to the opcrators receiver before the bridge is opened.

3. A telephone exchange system comprisinga trunk circuit including a'pair of talking conductors extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device for the link circuit, an operators telephone set at the second switchboard having the receiver thereof connected with the talking conductors, a direct current inductive bridge for the talking conductors, a manually operatedswitch at the second switchboard adapted when actuated to open the bridge thereby to cause the operation of the signaling device, and means responsive vto `the actuation of thel switch to open one of the talking conductors extending to the operators receiver before the bridge is opened and responsive to the restoration of the switch to normal position to close the opened talking conductor after the bridge has been restablished.

4. A telephone exchange system comprising a trunk circuit including a pair of talking conductors extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device for the link circuit, an operators telephone set at the second switchboard having the receiver thereof connected with the talking conductors, a direct current inductive bridge for the talking conductors, a manually operated switch at the second switchboard adapted when actuated to open the bridge thereby to cause the operation of the signaling device, mea-ns responsive to the actuation of the switch to open one of the talking conductors extending tothe cperators receiver before the bridge is opened, and a relay responsive to the restoration of the switch to normal position to close the one talking conductor after the bridge has been restablished.

5. A telephone exchange system comprisving a trunk circuit including a pair of con- Venergized to connect theureceiver of the operatorie telephone set with the talking conductors, a manually operated switch at the second switchboard adapted when actuated to open the bridge thereby to cause the operation of the signaling device and to denergize the first relay, and means responsive to the actuation of the switch to open one of the talking conductors extend- =ing to the operaters receiver before the bridge is opened and to maintain these'cond relay energized. l

G, A telephone exchange system comprising a trunk circuit including a pair of conductors extending from a first to a second switchboard, a link circuit at the irst switchboard, a signaling device for the link circuit, a direct current bridge for the talking conductors, inductive ineens in the bridge vincluding a relay energized when the link circuit is connected with the trunk circuit, an operators telephone set, a second relay energized while the iirst relay is energized to connect the receiver of the operators telephone set with the talking conductors, a manually operated switch at the second switchboard adapted actuated to open the bridge thereby to cause the operation of thesignaling device and to denergize the irst relay, a third relay responsive to the actuation of the switch to open one of the talking conductors extending to the operators receiver before the vbridge is open, and a circuit completed upon the energization of the third relay formaintaining the second relay energized.

7. A telephone exchange system comprising a trunk circuit including a pair of yconductors extending from a iirst to a second switchboard, a link circuit at the first switchboard, a signaling device for the link circuit, a direct current bridge for the talking conductors, inductive means in the bridge including a relay energized when the when lll)

link circuit is connected with the trunk cir- 1eme? the operators receiver' before the bridge is conductors, vinductive means inthe bridge including a relayj energized when the link circuit is connected withthe trunk.` circuit, anoperators telephone set, asecond relay energized .while thefirst ,relay isv energized to connect the receiver of the operators telephone set with the talking conductors, `a manually operatedv switch at the ,second switchboard, ,adapted when actuated to open the bridge thereby to cause the operation of the signaling device and toldenergizethe first relay, means responsive to the actuation of the switch to open one of the talking conductors extending to the operators receiver before the bridge is opened, a circuit established whilethe switch isA actuated for maintaining the second relay energized, and a relay responsive to the restoration'of the switch to normal position-to fclose the one talking conductor after the bridge has been restablished., v

9. A telephone exchange system comprisinga trunk circuit including a pair of talking conductors extending from a first to a second switchboard, a telephone set, a link circuit connecting the telephone set with the trunk circuit, a signaling device for the link circuit, an operators telephone set at the second switchboard having the receiver thereof connect-ed with the talking conductors, a direct current inductive bridge for the talking conductors, a manually controlled switch at the second switchboard adapted when actuated to open the bridge thereby to cause the operation of the signaling device, means connected in circuit with the inductive bridge upon the actuation of the switch to absorb the charge of current resulting from the discharge of the induc-v tive'bridge upon the opening-thereof, and means also responsive to the actuation of the switch to open one of the talking conductors extending to the operators receiver before the bridge is opened. y

10. A telephone exchange systemcomprising a trunk circuit including a pair of talking conductors extending from a first toa second switchboard, a telephone set, a link circuit connecting the telephone set with the trunk circuit, a signaling device for the link circuit, an operators telephone set at the second switchboard having the receiver n thereof connected with the talking conductors, a manually. controlled switch at the second switchboard adapted when actuated to open the bridge thereby to cause the 'operation of the signaling device,a condenser ,j

connected in circuit withthe inductivebridge upon Ltheactuatitmrof,the switchto absorb the charge of current resulting from the dis- Y chargeyof the inductive. bridge upon .the opening Athereof, meansgresponsive to ythe actuationof the switch to open one ofthe talking conductors extending to the4 operators receiver before the bridge is opened, and a relay responsive to the restoration of the switch to normal position to close the one talking conductor after the bridge has been restablished.

c l1. A telephone exchange system comprising a trunk circuit including a paii` of talking conductors extending from a first vto a second switchboard, a link circuit at the first switchboard connected -with the trunk circuit, asignal control relay in the link circuit energized when the link circuit is connected with the trunk circuit, an operat:

ring conductors "andthefc'onnected link circuit,`a locking circuit for thev relay established upon the energization thereof for maintaining the signal control relay energized while the operators telephone set is disconnected from the trunk circuit, and y means responsive to the subsequent connection of the operators telephone set with the trunk circuit to open the'locking circuit.

12. A telephone exchange system comprising a trunk circuit including a pair of talking conductors Y extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signal control relay in the link circuit energized when the link circuit is connected with the trunk circuit, an operators telephone ,set at the second switchboard, means for connecting and disconnecting theJ operators telephone set to and from the trunk circuit, a switch at the second switchboard, a relay thereat connected across the talking conductors by the momentary' actuation of the switch and. thereupon energized over a circuit including portions of the talking conductors and the connected link circuit, a locking circuit for the relay established upon the energization thereof for maintaining the signalv control relay enervrelay momentarily energized when the oper- Y irst switchboard connected With the trunk circuit, a signal control relay in the link circuit, an operators telephone set at the second switchboard, means for connecting and disconnecting' the operators telephone set t0 and from the trunk circuit, an energizing circuit for the signal control relay established While the operators telephone set is connected with the trunk circuit, a switch at the second switchboard, a relay thereat connected across the talking conductors by the momentary actuation of the switch and thereupon energized over a circuit including portions of the talking conductors and the connected link circuit, a locking circuit for the relay established upon the energization thereof for maintaining the, signal control relay energized While the operators telephone set is disconnected from the trunk circuit, and a relay momentarily energized When the operators telephone set is being subsequently connected With the trunk circuit to open the locking circuit.

14. A telephone eXchange system comprising a trunk circuit including a pair of talk- @epics of this patent muy be obtained for ve cents each, by addressing the Washingtonhc. l

set at the second switchboard, means .torV

connecting and disconnecting Athe operators telephone setto and from the trunk circuit, a bridge for the talking conductors' established While the'o'perators telephonev set is connected with the trunk circuit, an energiz- 1 ing circuit for the signal control relay including the bridge, a-switch'at the' second switchboard, a relayy thereat connected across the talking conductors bythe momentary actuation of the switch and Vthereupon energized over a circuit including portions of the talking conductors and the connected link circuit, a locking circuit for the relay established upon the energization thereof for maintaining the signal control relay energized While the operators telephone set is disconnected from the talking conductors, and a relay momentarily energized When the oporators telephone set is -being subse* quently connected With the trunk circuit to open the locking circuit.

In witness whereof, Ihereunto subscribe my name. f

'FREDERICK n. ANDERSON.

Commissioner of' Patente, 

